1. Field of the Invention
The invention relates to a device for blowing gases for regulating the clearances or gaps within a gas turbine engine.
2. Discussion of the Background
For some time it has been an aim to reduce the gaps between rotary and fixed parts of gas turbine engines and more particularly between the ends of blades and the opposing rings of the stator, especially in the turbines, in order to increase the efficiency of the engine, the thrust which it produces and the pumping reserve.
The gaps are variable during the operation of the engine between starting, transient states and the stable state, due to heating and centrifugal forces, which give rise to increasing mechanical and thermal deformations differing between the stator and the rotor. For this reason dynamic clearance regulating devices have already been designed, whereof the most widely used utilize a gas current, tapped from a portion of the engine, such as a compressor, and which circulates behind the stator rings, whereof the diameter is to be regulated. The gas cools or heats the rings, as a function of the engine part from which it comes and produces supplementary thermal deformations bringing said rings to the desired diameter. The extent of such deformations can be regulated with the tapped gas flow rate. Thus, gases can be tapped at several points of the engine and the corresponding channels are successively opened in order to obtain a deformation having the desired value. French patents 2 509 373 and 2 688 539 give a few examples of such configurations.
However, it has been observed that the thermal deformations produced are not always uniform, which can be attributed to a lack of homogeneity of the gas flow along the circumference of the ring, or a lack of temperature uniformity if it comes from several pipes issuing in front of successive ring portions.